Abstract: A position detection device of active magnetic bearings (AMB's) maintaining the position of a rotating shaft and comprising two sensing inductance coils, the position detection device comprising a programmable digital component for generating a 25 KHz square waveform signal, a current amplifier receiving the 25 KHz square waveform signal and injecting two identical control currents in the two sensing inductance coils, a differential amplifier for amplifying a voltage difference between the resulting voltages in the two sensing inductance coils and, depending on the displacement of the rotating shaft, an analog to digital (A/D) converter for delivering a position value from the voltage difference.

Abstract: A position detection device of active magnetic bearings (AMB's) maintaining the position of a rotating shaft and comprising two sensing inductance coils, the position detection device comprising a programmable digital component for generating a 25 KHz square waveform signal, a current amplifier receiving the 25 KHz square waveform signal and injecting two identical control currents in the two sensing inductance coils, a differential amplifier for amplifying a voltage difference between the resulting voltages in the two sensing inductance coils and, depending on the displacement of the rotating shaft, an analog to digital (A/D) converter for delivering a position value from the voltage difference.

Abstract: The present invention provides a circuit for monitoring harmonic distortion in the power supply of a synchronous electrical machine with permanent magnet excitation that comprises a rotor without a damper cage, a stator with first, second, and third windings, a frequency converter, and control circuits for controlling the frequency converter.

Abstract: The present invention provides a circuit for monitoring harmonic distortion in the power supply of a synchronous electrical machine with permanent magnet excitation that comprises a rotor without a damper cage, a stator with first, second, and third windings, a frequency converter, and control circuits for controlling the frequency converter.

Abstract: The invention relates to the selection of a source from a plurality of sources by means of shunt switches and series switches, which are respectively turned on and mined off, and vice versa. For access to, for example, four sources the device has two intermediate terminals B.sub.1, B.sub.2), one series switch (SE.sub.a, SE.sub.b) is arranged between the user installation and each of the two intermediate terminals, and each of the intermediate terminals is coupled to two sources (IN.sub.1, IN.sub.2 or IN.sub.3, IN.sub.4) by each time one series switch (SE.sub.1, SE.sub.2, SE.sub.3, SE.sub.4). Moreover, each source (IN.sub.1, IN.sub.2, IN.sub.3, IN.sub.4) is a.c. coupled to earth by a matching impedance in series with a shunt switch (Z.sub.1, SH.sub.1, or Z.sub.2, SH.sub.2, or Z.sub.3, SH.sub.3, or Z.sub.4, SH.sub.4). The device is used in CATV.